Predicting the damage to structures commonly found in Urban Environments to the effects of intentional or accidental small explosions is a difficult problem, often resulting in hazards to nearby personnel and equipment. Numerous commercial and military organization desire models that can predict the structural damage and characteristics of the debris generated by the various forces. In this SBIR Phase I, several HFPB (High Fidelity Physics Based) methods will be compared by simulating the breach of urban walls by small munitions causing (a) inert penetration, and (b) explosive penetration. Fast Running Models that mimic the results of the HFPB simulations will also be demonstrated. BENEFIT: In recent years, the US military finds itself more involved in urban warfare. In urban warfare or MOUT (Military Operations in Urban Terrain), armed forces have to exhibit caution so that their actions will not harm civilians and friendly forces in the area. These precautions exclude the use of large weapons and therefore the military is extremely interested in the use of more precise small weapons. These small weapons are often used to breach urban walls and can be inert projectiles or explosive projectiles (cased weapons) that a) detonate upon impact or b) set for a delayed detonation during partial penetration in order to maximize damage. The physics of the inert or explosive impacts and the resulting breakup and debris generation of these munitions is very complex and validated numerical methods do not yet exist. Therefore, there is a need to develop validated small munitions models capable of determining the consequences of their use in order to assist military planners and soldiers in the field. In this project, we proposed to develop FRMs (Fast Running Models) to predict (a) hole size, (b) amount of material removed, (c) probabilistic debris mass and velocity distributions due to inert and explosive penetration of urban walls by small weapons.